1. Field of the Invention
The present invention relates to stripping and cleaning compositions for the removal of residue from metal or dielectric surfaces in the manufacture of semi-conductors and microcircuits. More particularly, the invention provides a novel inhibition system which prevents corrosion of the metal and redeposition of residue on the substrate.
2. Description of the Prior Art
Conventionally in the manufacture of semi-conductors and microcircuits after the etching step, the residual etchants and photoresists must be removed without corroding or dulling the surface of the metallic circuitry or chemically altering the substrate.
Resist stripping and cleaning agents comprising mixtures of aromatic solvents and basic amines are known. While these resist stripping agents are effective in removing the photoresist residues, they also tend to corrode the metal or metal alloy conductor such as copper, aluminized silicon dioxide and/or titanium. It has been proposed in some stripping compositions to employ hydrogen fluoride to reduce the rate of metal corrosion However, hydrogen fluoride attacks titanium metal, requires careful handling by personnel and creates disposal problems. Moreover, commercially available photoresist stripping compositions have required unduly long residence times or repeated applications in order to remove certain coatings. In addition, various coatings have resisted removal from certain substrates with the available stripping compositions.
As the processing size is becoming finer in sub-micron devices, i.e., more transistors/cm2, the etching conditions and the necessity to remove post etch residues become more critical. The photoresist becomes more susceptible to damage and more difficult to remove under the more stringent conditions. Thus, stripping/cleaner formulations must be improved including providing more efficient corrosion inhibitors. Known metal corrosion inhibitor additives (i.e. phenol derivatives such as catechol, pyrogallol, gallic acid, resorcenol, and beta-naphthol) glucose and azoles such as, benzotriazole etc., in semiconductor stripper-cleaners in semi-aqueous solvent blends, do not maintain an acceptable level of corrosion inhibition in the presence of high levels of water. With conventional inhibitors exceeding about 25 weight percent water results in unacceptable corrosion rates for aluminum, aluminum alloys and copper. Semiconductor device performance and yield are strongly dependent on maintaining the designed line width. Unacceptable line width loss results in yield loss. Higher levels of water improve the removal rate of etch inorganic residue, however, this had to be balanced against line width loss.
U.S. Pat. Nos. 5,496,491, 5,556,482 and 5,707,947 to Ward, et al., which are herein incorporated by reference, disclose organic stripping compositions for photoresists comprising organic polar solvents and basic amines which include inhibitors which form coordination complexes with the metal. The corrosion inhibitors disclosed are phenol derivatives are weak acids which deprotonate in solutions with a pH about 9 forming mono- and di-anions which can chelate with metal cations, forming stable five, six and seven membered rings.
Benzoic acid and substituted benzoic acids have been studied as interfacial corrosion inhibitors for copper in perchloric acid (HClO4), R. K. Dinoppa and S. M. Mayanna, Journal Of Applied Electrochemistry, 11 (1981) p. 111-116 but never tested in the field of stripper/cleaner compositions for the removal of photoresists from semiconductors and microcircuitry elements.
There exists a need to provide a photoresist stripping/cleaning composition which provides improved corrosive prevention to metals and metal alloys, as well as, efficient and substantially complete removal of a wide variety of organic polymeric photoresist and inorganic materials while being chemically inert to the substrate.
In accordance with the present invention there is provided aqueous acidic and basic stripping and cleaning compositions useful in the semiconductor or microcircuitry industry for removing photoresists and other residues having improved corrosion inhibition, are useful in acidic. stripping and cleaning compositions, are free of oxidants.
The inhibitors which are employed in the stripping and cleaning compositions of this invention are a unique group of aromatic carboxylic acids and their derivatives selected from ammonium benzoate, benzoic acid, phthalic acid, phthalic anhydride, isophthalic acid and mixtures thereof in an effective corrosion inhibiting amount.
Advantageously, the photoresist stripping and cleaning compositions which comprise water basic amines include alkanol-amines, hydroxylamines and mixtures thereof. The compositions of he invention are particularly useful for removing inorganic residues on metal or dielectric substrates.
It is an object of this invention to provide improved stripping and cleaning compositions which effectively and efficiently remove residues from subsrates without redeposition.
It is another object of this invention to provide an improved stripping and cleaning compositions which is not corrosive to either metals, metal alloys or dielectric substrates.
It is still another object of the present invention to provide a stripping and cleaning composition which inhibits redeposition of metal ions.
It is a further object of the present invention to provide a corrosion inhibitor which effectively can be used in basic or acidic stripping and cleaning compositions.
It is still a further object of the present invention to provide a corrosion inhibitor for stripping and cleaning compositions which maintain an improved level of corrosion inhibition in the presence of high levels of water.
Yet another object of the present invention is to provide corrosion inhibitors for semi-aqueous photoresist stripping and cleaning compositions which are less expensive and are effective at low concentrations and low temperatures.
Yet a still object of the present invention is to provide an aqueous stripping and cleaning composition for aluminum and copper foils which have a high cleaning efficiency in aqueous formulations with reduced toxicity.